Missions (Hardmode)
General mission types in hardmode are mostly unchanged compared to vanilla.
UFO Landed Assault
Some Alien UFO missions involve landings. Observing a UFOs speed and height can help in determining if a UFO is in the process of attempting a landing, however in some circumstances the UFO may be merely conducting a low level sweep and will not land.
A UFO that lands is far more difficult to assault, but the UFO will suffer no loss of onboard equipment or resources, thus offering a far greater reward than a crashed UFO.
Furthermore, the entire crew compliment will be alive and healthy, ergo they will offer greater resistance. Furthermore a UFO may land during the night, further enhancing the difficulty of the mission. In addition a landed UFO will only remain on the ground for a short duration, making it risky to attempt to wait for the landing site to reach morning.
UFO Crash Site Assault
Whenever a UFO is shot down, assuming it is not destroyed outright due to overdamage, a crash site assault becomes available.
A UFO brought down will suffer a variable amount of damage to onboard equipment and crew numbers in addition to possible structural damage to the craft, which may make assaults on it easier. This represents a double edged sword as a crashed UFO is relatively easier to secure than a landed one, but it will offer less recoverable resources.
Be wary that shooting down UFO's has a chance to trigger a future alien retaliation mission. Avoid shooting down craft near bases you do not want to be attacked.
Alien Base Assault
As the invasion proceeds the aliens will construct ground bases on Earth to advance their goals. A successful assault on an alien base is absolutely vital in the early game in order to secure research data and resources to progress the tech tree.
The aliens are guaranteed to construct an alien base within the same region as X-COM's first base within the first month. This is to guarantee that X-COM can assault an alien base and advance the tech tree.
Unlike vanilla, base assaults tend to be larger in size and hold a larger defensive force. In addition to how early a player must assault one, expect a long operation. The usage of alloy ammunition is vitally required for success for these early game assaults.
Terror Mission
Terror missions require X-COM to defeat a large contingent of alien terror troops while attempting to save as many civilians as possible. Failure to attend to a terror mission will result in major negative political consequences for X-COM.
Hardmode terror missions feature significantly larger maps and a larger contingent of civilians at risk, potentially up to 24.
Civilians remain unarmed and cannot defend themselves. Do note that a stunned civilian still counts as being alive at the end of a mission.
Due to alternations from the mod, even a successful terror mission will still see X-COM suffer a negative score/political penalty, it is very unlikely for X-COM to gain a positive score out of a terror mission, with a best case scenario being a even score of around 0. Ergo terror missions put more pressure on X-COM to not only succeed here, but to succeed elsewhere to counteract the consequences of a terror mission.
Terror missions are more dangerous in hardmode due to a wider range of unique terror forces, with the possibility of encountering multiple terror troops that would normally not work together in vanilla. Furthermore, failure to attend a terror mission will confer a larger negative score to X-COM than vanilla, around a negative 2000 score. If X-COM cannot make an effort to attend a terror mission, expect major consequences to your score. (landing and aborting the mission will confer a similar negative score)
X-COM Base Defence
Base defence missions operate similarly to vanilla, expect a large contingent of enemy forces in addition to terror troops.
Cydonia or Bust
The battle to end the war. Expect a longer, gruelling, version compared to vanilla with a larger contingent of mixed enemy troops.